1. Field of the Invention
The present invention relates to protocols used to transfer audio data from one module to another module within a printed circuit board (PCB) or an integrated circuit (IC).
2. Related Art
Traditional processing of audio signals transferred between audio modules within a PCB or an IC typically requires conversion of the related audio signals to an inter-IC sound (I2S) standard or a similar format.
A variety of products are commercially available that utilize audio data, especially at the PCB and IC levels. These products can include set top cable boxes, compact disk players, digital audio tape devices, digital sound processors, and digital televisions, etc. The digital audio signals processed within these systems are shared between numerous PCBs and ICs. During processing, audio signals are shared between internal components within the PCBs or ICs. These components can include, for example, analog-to-digital converters (ADCs), digital-to-analog converters (DACs), error correction devices, digital filters, digital input/output (I/O) interfaces, and the like.
I2S is one technique intended to standardize the format of audio data transferred between these internal components. I2S also defines a structure for a data bus used to transport this audio data. With I2S, a line serial bus is used to transfer the audio signals from one component, or module, to another. In I2S, a 3-line serial bus (as opposed to a greater number of lines) is used to minimize the number of pins required on the IC and to keep wiring simple. This 3-line serial bus includes a line for 2 time-multiplexed data channels, a word select line, and a clock line.
PCB and IC level components implementing the widely accepted I2S standard must therefore convert all incoming audio data signals into the I2S format. The conversion enables the audio data signals to be transmitted across the 3-line serial bus. As the speed at which micro-electronic large scale integrated (LSI) devices operate increases, the time required to perform the I2S conversion becomes a critical system limitation. The chip space required to accommodate the three I2S pins has become equally burdensome. Although other serial data bus designs are available, even some with 1-line data links, most are too complex or lack sufficient flexibility for extensive use.
What is needed therefore is a data bus that can be used to transfer audio data that minimizes the complexities and amount of hardware required for transferring this audio data between PCB and IC modules. What is also needed is a suite of protocols to support this new bus in order to more efficiently transfer data between the modules, ultimately reducing the number of chip pins.